Fan CFM ratings

Im in the market for a new fan. Im looking at the 6" from HTG thats rated at 424 cfm, which sounds real good. I assume that rating is without any ducts attached, but how would it compare to a squirrel cage style blower once the duct and carbon filter are attached?

http://www.htgsupply.com/Product-GrowBright-6in-High-Velocity-Inline-Fan.asp

http://www.htgsupply.com/Product-465-CFM-ActiveAir-Blower-System.asp

youll want that inline fan bro, youll be happy with it....htg supply are pretty decent on their prices too good choice

it is rating without ducting
and inlines or easier to use and small then squirrel cages and make less noise